Carbonate Modified Compositions for Reduction of Flue Gas Resistivity

Abstract

Herein is described a composition effective for reducing the particulate resistivity of hydrated lime and capturing acidic gases from flue gas. The composition can include a supported carbonate that comprises 5 wt. % to 50 wt. % of a carbonate and 50 wt. % to 95 wt. % of a support; where the carbonate is an alkali metal carbonate selected from the group consisting of a carbonate, a bicarbonate, and a mixture thereof. The composition can be prepared by admixing the carbonate and the support with sufficient water and then drying. The composition can be used alone or with hydrated lime for reducing the concentration of acid gases in flue gas.

1 . A composition effective for reducing the particulate resistivity of hydrated lime and capturing acidic gases from flue gas, the composition comprising:
 a supported carbonate that comprises 5 wt. % to 50 wt. % of a carbonate and 50 wt. % to 95 wt. % of a support;   wherein the carbonate is an alkali metal carbonate selected from the group consisting of a carbonate, a bicarbonate, and a mixture thereof.   
     
     
         2 . The composition of  claim 1 , wherein the alkali metal carbonate is selected from the group consisting of sodium sesquicarbonate, sodium carbonate, sodium bicarbonate, and a mixture thereof. 
     
     
         3 . The composition of  claim 1 , wherein the supported carbonate consists essentially of a support selected from the group consisting of a silicate, an aluminate, an aluminosilicate, and a mixture thereof; and an alkali metal carbonate selected from the group consisting of sodium sesquicarbonate, sodium carbonate, sodium bicarbonate, and a mixture thereof. 
     
     
         4 . The composition of  claim 3 , wherein the supported carbonate comprises 25 wt. % to 35 wt. % of the alkali metal carbonate and 65 wt. % to 75 wt. % of the support. 
     
     
         5 . The composition of  claim 4 , wherein the support is selected from the group consisting of bentonite, montmorillonite, kaolinite, and a mixture thereof. 
     
     
         6 . The composition of  claim 4 , wherein the composition is an admixture of the supported carbonate and hydrated lime;
 wherein the admixture comprises 1 wt. % to 25 wt. % of the supported carbonate.   
     
     
         7 . The composition of  claim 6 , wherein the supported carbonate has a particle size and density, each, approximately equal to a particle size and density of the hydrated lime. 
     
     
         8 . The composition of  claim 7 , wherein the admixture consists essentially of 1 wt. % to 25 wt. % of the supported carbonate and the hydrated lime. 
     
     
         9 . A process of manufacturing a supported carbonate comprising:
 admixing a support and an alkali metal carbonate selected from the group consisting of a carbonate, a bicarbonate, and a mixture thereof;   providing sufficient water to the admixture to dissolve at most 50 wt. % of the carbonate; and then   removing sufficient water from the admixture to provide a dry, flowable particulate.   
     
     
         10 . The process of  claim 9 , wherein admixing comprises mechanically shearing the support and the alkali metal carbonate. 
     
     
         11 . The process of  claim 9 , wherein sufficient water is added to the admixture to dissolve at most 25 wt. % of the alkali metal carbonate. 
     
     
         12 . A process wherein acidic gases are removed from a flue gas, the process comprising:
 injecting, into the flue gas at a location upstream of an electrostatic precipitator (ESP), a composition that includes a supported carbonate which comprises an alkali metal carbonate selected from the group consisting of a carbonate, a bicarbonate, and a mixture thereof; and which comprises 5 wt. % to 50 wt. % of the alkali metal carbonate and 50 wt. % to 95 wt. % of the support; and then   collecting fly ash from the flue gas in the ESP.   
     
     
         13 . The process of  claim 12 , wherein the composition injected into the flue gas is an admixture of the supported carbonate and hydrated lime;
 wherein the admixture comprises 1 wt. % to 25 wt. % of the supported carbonate.   
     
     
         14 . The process of  claim 12  further comprising injecting hydrated lime into the flue gas. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . (canceled)